I live in St.louis, MO. The engine is out of the truck now and being rebuilt by Mike Christiansen. He's got it torn apart now. Told me the crank and one rod are destroyed. The block did not get hurt though. Going to meet with Mike today to decide what direction to go in for the rebuild.
Bobby
Get a standard crank and have it machined using the specs/clearances I pasted below. Twice I've tried to use a stock 4.3 crank in standard and the main bearing clearances were way too tight the way they came. While you may get by, it could just as easily fail on you right away.
For the crankshaft, you need to find yourself one from a non balance shaft 4.3 engine be it from a regular 4.3 or syty specific motor and get yourself some L35 connecting rods at the very least. Stock syty rods will generally bend (fail) before a stock syty piston fails. A stock syty piston will normally fail before you bend an L35 rod. (I haven't heard of a L35 rod bending yet but anything can happen when you ping under boost). The L35 rods will need to have the wristpins pressed out to seperate them from stock 4.3 pistons. Don't plan on using the pistons from the L35 motor. You need to use stock syty pistons at the very least or some TRW's like Big Dave did. You can also buy the rods new from GM. Do a search for L35 rods at syty.net or google for a part number. I got a set of L35 rods out of a 2000 4.3 engine for a stockish build a while back. I think GM started using those rods from 93 up in non syty applications. If you manage to grab an old L35 motor, you could also bolt the heads onto your syty motor for a few extra HP. The L35 heads are better than stock. A dead giveaway to ID those heads is a half moon looking notch at the top of the intake ports on the heads where the injector would spray with an upper intake installed. On my built motor truck I used eagle h-beam rods and the JE severe duty pistons at 8.5:1 compression. Also I used the vortec heads from the 2000 4.3 motor but that required some extensive modifications to do.
Make sure your main caps are syty specific! Use them at the very least. ( I would go with 2 bolt billet caps at the very least though) They have the letter "N" cast into them I believe. Personally, I went with Diamond racing billet racing 4 bolt caps on my center two. Use ARP bolts/hardware where you can. Don't use cometic head gaskets. Use the stock syty replacement head gaskets (victor?) And if for some crazy reason you decide to use head studs, go with high temp loctite #567 to seal them!! Been there done that.
Also, be careful with who you mix up with when it comes to socalled "syty vendors". Do your homework, use the search feature and PM people for feedback before you get involved with anyone that claims to be a "vendor"! Starting a thread about this at syty.net is useless because for the most part, people that have been screwed are too afraid to step up and publically report their bad experiences. There are a couple guys out there that have screwed many people over and will not hesitate to screw you. Very seldom will a bad guy get called out, but when they do, many uneducated people tend to jump on the bandwagon to defend the individual for the reason that "syty vendors are rare and non existant these days."
Besides, you don't need to be sending your motor halfway across the world just to find out something is wrong when you get it back and install it then you have to pull your engine and send it back. Get the work done by a local reputable machine shop and be prepared to check his/her work at least with a plastigauge on your rod/main bearings. The plastigauge isn't the most accurate measuring tool but it will alert you to obvious BIG problems before you go and install the engine in the truck and spin a bearing.
I hope this helps and if any of my above info is inaccurate, someone please let me know so I can correct it!!
Here's some specs for your builder to go by:
Type: V6
Disp.: 262 C.I. (4.3L)
Horsepower: 280 BHP @ 4400 (Syclone) 285 BHP @4400 (Typhoon)
Torque: 350 lb-ft @ 3600 (Syclone) 350 lb-ft @ 3600 (Typhoon)
RPO: LB4
Bore: 4.00
Stroke: 3.48
Comp. Ratio: 8.35:1
Firing Order: 1-6-5-4-3-2
Oil Pres. (Min) 6 psi@ 1000 RPM, 18 psi@ 2000 RPM, 24 psi@ 4000 RPM
CYLINDER BORE:
Diameter: 3.9995-40025
Out of
Round: .001 (production) .002 (service)
Taper: .001
PISTONS:
Clearance: .0015-.0030
PISTON RING: Compression: Groove Clearance: .0012-.0032 Gap: .010-.020 (top) .010-.025 (2nd) Oil: GC: .002-.007 Gap: .015-.055 PISTON PIN: Diam: .9270-.9273 Piston Clearance: .0002-.0007 Rod Fit: .0008-.0016 Interference
CRANKSHAFT:
MAIN JOURNAL: Diam: #1 2.4484-2.4493
#2 #3 2.4481-2.4490
#4 2.4479-2.4488
Taper: .001 max
Out of Round: .001 max
MAIN BRG. CLEARANCE: #1 .0010-.0015 #2#3 .0010-.0025 #4 .0025-.0035
CRANK END PLAY: .002-.006
CRANKPIN: Diam: 2.2487-2.2497
Taper: .001 max
OOR: .001 max
ROD CLEARANCE: .0013-0030
SIDE CLEARANCE: .006-.014
CAMSHAFT:
LIFT +- .002 Intake .357 Exhaust .390 Journal Diam: 1.8682-1.8692 End Play .004 -.012
VALVE SYSTEM:
Lifter Hydraulic Rocker ratio 1.5:1
Lash Adj. One turn down from zero Face Angle 45 deg.
Seat Angle 46 deg.
Runout .002 max
Seat Width 1/16 to 1/32 Stem clearance .0010-.0028 Spring length 2.03 Valve Spring Pres. 76-84 lbs @ 1.70 in Closed 194-206 lbs @ 1.25 in
Open Installed height 1 23/32
Valve Spring Damper: Free Length 1.86 # coils 4